Sulphur can be solidified into easily handled slates by pouring molten sulphur on to an endless belt that travels in a generally horizontal direction. The belt speed and length, and the thickness of the layer of liquid sulphur are coordinated such that ambient air and water cools the sulphur to below its solidification point (245.degree. F.) before the sulphur reaches the end of the belt. The solidified sulphur fractures and falls off the end of the belt. Apparatus of this general type is disclosed in U.S. Pat. No. 3,832,145, which is assigned to the same assignee as this invention.
Molten elemental sulphur recovered by the treatment of hydrogen sulphide bearing natural and industrial gases or by the Frasch process ordinarily has a temperature in the range of 300.degree. F. To reduce the heat transfer load on the belt-type slating installations, it is desirable to reduce the temperature of the molten sulphur to close to its solidification point before pouring it on to the belt. In the past, it has not been practical to attempt to cool sulphur to within less than 15.degree. F. above its solidification point. The reason is that prior art sulphur cooling equipment employed ambient air as the cooling fluid, and the heat absorbing ability of such air varies substantially as its temperature and relative humidity vary. To minimize the possibility of a sharp increase in the cooling capacity of the ambient air plugging a system by solidifying the sulphur, these systems are designed to cool the sulphur to not less than 15.degree. F. above its solidification point. Blowing air into hot molten sulphur in metal equipment also accelerates corrosion, and can increase pollution, and fire, explosion and other safety hazards.